Internal combustion engine



March 24, 1942. J. G. KIMMEL INTERNAL COMBUSTION NGINE Filed Feb. 28, 1939 2 Sheets-Sheeb 1 QQM lll

RNW

March 24, 1942. J. G. KIMMEL 2,277,113

l INTERNAL COMBUSTION ENGINE Filed FSB. 28, 1939 2 Sheets-Sheet 2 Patented Mar. 24, 1942 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE t Joseph G. Kimmel, Sarasota, Fla..

Application February 28, 1939, Serial No. 259,013

17 Claims.

This invention relates to internal combustion engines, and more particularly to a method and apparatus for controlling the temperatures of the combustion chamber walls of such engines. The present application is a continuation-inpart of my copending application Serial No. 751,397, filed November 3, 1934, now abandoned.

It is the common practice to control the temperature of an internal combustion engine cylinder by passing a cooling liquid throughpassages around the cylinder and cylinder head to transfer theheat from the combustion chamber walls to the cooling liquid, and then to circulate the heated liquid through a suitable radiator or the like. The cooling fluid is then returned in a cyclic operation to the passages around the cylinder and cylinder head. This is the generally accepted method of controlling the temperatures of an internal combustion engine and while it is y practicable and fairly satisfactory in operation,

it is open to several disadvantages and is relatively ineicient.

The disadvantages of` a conventional engine cooling system of the type referred to are well known and recognized. For example, the capacity of the conventional cooling system is relatively great since the inherent characteristics of the system are such as to require a relatively large volume of cooling liquid to prevent overheating of the engine under maximum load conditions. Therefore, the quantity of cooling liquid is too great under all other heat load conditions and accordingly internal combustion engines operate under most conditions at temperatures below the most efficient temperature of operation. There are other inherent disadvantages in a system of this character which need not be discussed in detail.

An important object of the invention is to provide a novel method of controlling the flow of cooling fluid around the cylinder of an internal combustion engine so as to maintain the combusti-en chamber Walls within relatively close limits of minimum and maximum temperatures adjacent the temperature of maximum operating efficiency.

A further object is to provide a method of controlling the rate of flow of the cooling fluid and the nature of such flow so as to effectively control the temperatures of the combustion chamber walls.

A further object is to provide a method of the character referred to for utilizing increasing temperatures of the combustion chamber walls for causing the flow of the cooling liquid to belcombustion chamber walls Within the desired limits.

A further object is to provide a method of the character referred to which is fully automatic in operation to control the cooling fluid in such a manner as to maintain a more uniform optimum operating temperature in the combustion chamber walls under varying heat load conditions.

A further object is to provide a novel apparatus for controlling the rate of heat transfer to a fluid temperature controlling medium of an internal combustion engine to maintain a more uniform optimum operating temperature in the combustion chamber walls.

A further object is to provide a novel apparavtus of the character referred to wherein the transfer of heat from the combustion chamber walls to the uid medium takes place far more rapidly under heavy heat load conditions than is possible with conventional cooling systems, thusproviding for the efficient controlling of the engine temperatures with a much smaller volume of the fluid medium.

A further object is to provide a temperature controlling system for internal combustion engines wherein the maintenance of combustion chamber wall temperatures within relatively close minimum and maximum limits results in a substantial reduction in the internal stresses in the cylinder walls, thus permitting the use of relatively thinner walls.

A further object is to provide an internal combustion engine temperature regulating system which functions to permit the engine to warm up rapidly, and which eliminates the loss of the temperature controlling fluid.

Other objects and advantages of the invention f will become apparent during the course of the following description.

In the drawings I have shown several embodiments of the invention. In this showing:

Figure 1 is a schematic view showing a preferred form of system, parts being shown in section,

Figure 2 is a detail central vertical sectional view through an internal combustion engine cylinder, Figure 3 is a similar view shown in connection with a modified type of temperature controlling system, and,

Figure 4 is a fragmentary sectional view of the .head end of an internal combustion engine cylinder showing a modified type of fluid pas- Referring to Figures 1 and 2, the numeral I8 designates a cylinder as a whole o'f an internal combustion engine comprising a relatively thin cylinder liner I I surrounded by a body of a metal I2 of high heat conductivity such as copper or aluminum. A helical tube I3 is embedded in and bonded to the metal I2 and the latter ls bonded to the liner II, thus providing an efficient means for transferring heat from the cylinder liner to the iiuid to be referred to which flows through the tube I3. The metal I2 may be surrounded by a shell or Jacket I4. One of the valve of the engine is indicated by the numeral I5 and controls communication through a port I6.

The cylinder is provided with a head I1 in which is embedded a coil I8 which forms a continuation of the coil I3 and may be connected thereto as at |9. The coil I8 has communication with a iiuid pipe 26 through which uid flows from the coils I3 and I8. The lower end of the coil I3` is provided with an inlet pipe 2| (Figure l).

The pipe 2| receives cooling or temperature controlling iiuid flowing thereto through a control valve indicated as a whole by the numeral 22. The control valve receives fluid through a pipe 23 and the uid is pumped through this pipe by a suitable pump 24, preferably of the rotary positive type and provided with a drive shaft 25 which may be driven by some part of the engine I0. The intake pipe 26 of the pump receives fluid froma pipe 21 one end of which communicates with a condenser indicated as a whole by the numeral 28 and to be referred to in detail later. The other end of the pipe 21 communicates with a pipe29 one end of which leads to an expansion chamber 33 in which air is trapped, as will be described. The other end of the pipe 29 leads to the outlet side of a pressure relief valve 3| and the pressure at which this valve opens may be adjusted by a handle 32. Any desired form of pressure relief valve may be employed and forms no part per se of the present invention. 'Ihe top of the relief valve, as shown in Figure 1, communicates with the bottom of the valve 22 through a pipe 33.

T'he valve 22 is provided therein with a chamber 34 which communicates with the pipe 2| and communication between this chamber and the interior ofthe main casing of the valve 22 is controlled by valve elements 35. These valve elements are normally slightly spaced from their seats so that some circulation of fluid from the pump 24 to the pipe 2| will take place at all times. The valves 35 are adapted to be opened to a greater extent as the heat load of the engine increases. The valves 35 are carried by a stem 36 extending upwardly for connection with a diaphragm 31 housed by the upper end of the control valve and covered by a cap 38 with which it combines to form a pressure chamber 39. A spring 40 urges the stem 36 upwardly to tend to close the valves 35, but as previously stated, these valves never entirely close and may be provided with any suitable means such as a collar 4| to limit the upward movement of the valves. The stem36 operates in a bearing 42 against which the spring 40 engages, the bearing being threaded in the valve casing to permit adjustment .of the tension of the spring. A pressure pipe 43 communicates at one end with the chamber 39 and has its other endconnected toa temperature bulb 44 preferably arranged in the cylinder head I1. The bulb 44 is preferably located at such point as to reflect the temperature of the inner wall of the hottest part of the engine combustion chamber. It will be apparent that as the temperature rises at the bulb 44, pressure in the pipe 43 and-chamber 39 will force the diaphragm 31 downwardly to open the valves to a greater extent and thus permit a more rapid flow of iluid through the pipe 2| to the lower end of the coil I3. The capacity of the pump 24 is such that it obviously pumps uid at a rate greater than can be taken care of past the valves 35', and the excess fluid is bypassed around the pump by the relief valve 3| and pipes 29 and 21.

The condenser 28 comprises a main casing 45 having a lower head 46 above which is arranged a plate 41 forming therewith a chamber 48 with which the upper end of the pipe 21 communicates. An upper head 49, forming the top of the condenser, is arranged over a plate 50 and forms therewith a chamber 5I communicating with the pipe 20, as shown in Figure l.

'I'he plate 58 slopes downwardly toward its center to drain liquid into a vertical pipe 52, the lower end of which extends through the plate 41 to return liquid to the chamber 48. The pipe 52 is surrounded by a plurality of pipes 53 all of which extend through the plate 41 to communicate with the chamber 48, but the upper ends of the pipes 53 extend upwardly into the chamber 5I to receive vapor therefrom. Upper and lower headers 54 and 55 are arranged in the casing and tubes 56 are connected between the GII headers 54 and 55 as shown in Figure l. Each tube 56 surrounds one of the pipes 53 in concentric relation therewith. The upper header 54 forms with the plate 50 a fluid chamber 51 while the lower header 55 forms with the plate 41 a lower chamber 58.

The upper chamber 51 communicates through a pipe 59 with a heat exchanger 68 which may be a radiator, cooling tower or the like. It will become apparent that if a suitable supply of water is available as the condensing liquid, the heat exchanger 6|) may be eliminated. A pipe 6| leads from the heat exchanger to a pump 62, similar to the pump 24, and preferably of the rotary positive pump type. This pump is provided with a driveshaft 63 which may ybe driven by the internal combustion engine.

The outlet of the pump 62 is connected by a pipe 64 to a control valve unit 65. A pipe 66 connects the interior of the valve unit 65 with a pressure relief valve 61 of any desired type, adjustable through a handle 68. The relief valve 61 may -be similar to the valve 3| and any desired type of relief valve may be employed. 'I'he outlet of the relief valve 61 is connected by a pipe 69 to the pipe 6| to provide a by-pass for excess fluid delivered by the pump 62 to the valve unit 65, as will become apparent.

The valve unit 65 is similar to the valve 22 and is provided with a cham-ber 16 communicating with the chamber 58 of the condenser to deliver liquid thereto. Communication through the valve 65 is controlled by a pair of valve elements 1I carried by a stem 12 extending through a bearing 13. 'I'he valve unit 65 is provided with a diaphragm 14 capped as at 15 to provide a chamber 16, and a spring 11 is arranged between the diaphragm 14 and bearing 13 to tend to urge the valves 1I toward closed position. The bearing ent in the pipe 2I and tube I3 as will be referred to later.

A simplified form of system is shown in Figure 3, the results of the use of this system being far more satisfactory than conventional engine cool# ing systems but not as satisfactory as the results obtained with the system shown in Figure 1l Referring to Figure 3', the cylinder proper is indicated by the numeral 80 and the engine is provided with a cylinder head 8|. The head may beformed of a metal of high thermal conductivity such as copper or aluminum, and the cylinder is surrounded by a jacket 82 of similar metal which may be cast around the cylinder 80, or may be pre-cast and shrunk thereon. A coil of tubing 83 -is embedded in the jacket 82 and is connected to one end of a similar coil 84 embedded in the head BI. These two coils form continuations of each other as in the form of the invention previously described.

The lower end of the coil 83 is connected to one end of a pipe 85 in which is preferably arranged a check valve 86 to prevent the surging of the fluid in the system, as will become apparent. 'I/he pipe 85 leads to a suitable condenser 81, which may be an ordinary radiator. The top of the condenser 81 is connected by a pipe 88 to the end of the coil 84. A pipe 89 connects the top of the condenser to an expansion bulb or chamber 90 provided with a cap 9| which may be in'the form of an adjustable relief valve through which the system may be filled with liquid s-uch as water and through which the temperature of the water may be regulated in a manner to be described. The level of the liquid normally is substantially at the height indicated by the dotted line 92.

The use of coils for thepassage of the uid around the cylinders is advantageous since a tube with relatively thin Walls can carry safely the highest pressure which will be used in the system. In smaller engines in which moderate pressures will be present in the uid systemthe tubes may be eliminated in favor of a structure such as that shown in Figure 4. The cylinder is indicated by the numeral 93 and surrounds a liner 94 and the inner surface of the cylinder 93 may be provided with a helical groove 95 forming with the adjacent Wall of the liner 94 a helical conduit for the circulation of iluid around the cylinder liner.

The operation of the form of the inventionshown in Figures 1 and 2 is as follows:

The entire engine cooling system is filled with liquid, such as Water, with the exception of the expansion chamber 30 which is filled' with air. As the engine warms up, vapor collects in the upper chamber I of the condenser and in the tubes 52 and 53, thus creating a pressure which displaces liquid in the system into the expansion chamber 30 to compress the air therein. As the pressure increases due to the heating and loading of the engine, the pressure in the temperature regulating system increases up to a maximum point of balance to be referred to latent The stop member 4I (Figure l) limits closing` movement of the' valves 35 so that the continuous operation of the pump 24 by the engine I0 causes. at least some circulation to take place through the helical tube I 3 (Figure 2) even when the motor is rst started in operation. The positions of the valves 35 are temperature controlled by the temperature bulb 44. As the walls of the combustion chamber become hotter, the temperatuer bulb iiuid expands to create a pressure in the pipe 63, and this pressure is transmitted to the diaphragm chamber 39 to open the valves 35 to a greater extent. For any given speed of the engine the pump 24 will cause a flow of liquid at least equal to the maximum demands of circulation through the helical pipe I3 as will become apparent, and under most conditions, therefore,

' there is `an excess amount of liquid pumped in proportion to the opening of the valves 35 and the excess liquid beingpumped creates a pressure in the body of the valve unit 22 to open the relief valve 3I and thus by-pass liquid around to the intake side of the pump 24.

Depending upon the positions of the valves 35, as determined in accordance with engine temperatures in the manner stated, liquid will be pumped through the pipe 2I .to the lower end of the 'helical tube I3, thence through this tube and through the tube I8 of the cylinder head,Y

and the fluid 4flows through the pipe 20 to the upper condenser chamber 5I.- Any water in the fluid reaching the chamber 5l will ow down the inclined surfaces of the plate 58 and thus drain downwardly toward the bottom chamber 48 through the pipe 52. The vapor flowing into the chamber 5I will flow downwardly through the pipes 53 to be condensed in a manner to be described for recirculation through the chamber 48, pipes 21 and 2B and pump 24. y i

A condensing liquid, preferably water, is circulated through the system including thev pipes 56, chamber 51, pipe 59, heat exchanger 60, pipe 6I, pump S2, etc. The heat exchanger 60 is employed `for dissipating heat from the condensing liquid and where ample water supply is available the heat exchanger may be dispensed with and Water may be fed to the pipe 6I and discharged from the pipe 59.

The mechanism for controlling the rate` of flow of the condensing liquid is similar to the mechanism described for controlling the flow of the fluid for controlling the temperature of the engine except that the positions of the valves 35 are controlled by the temperature of the combustion chamber walls of the engine While the positions of the valves 1I are controlled by pressure in the engine circulating system, and more particularly by the pressure adjacent the inlet endl.;l The pump 62 may be conveniently'vv of the coil I3. driven from any part of the engine I0 and normally pumps condensing liquid throughthe pipe 84 at an excessive rate in 'order to provide the maximum condensing action in the condenser when desired. The excess liquid pumped into the valve unit 85 creates a pressure therein which opens the relief valve 61, thus by-passing the liquid through the pipe 69 to the intake side of the pump 62.

The stop member 'I8 prevents complete closing of the valves 1I and accordingly at least some circulation of condensing liquid is maintained through the condenser pipes'56, each of which surrounds one of the vapor pipes 53. As the pressure in the temperature controlling system, and more particularly the pressure in the portion of the coil I3 surrounding the combustion chambers, increases this pressure will be communiof liquid and a turbulent flow the rate of circulation of the condensing liquid through the pipes 56. This action obviously causes an increased rate 'of condensation of vapor in the pipes 53 and tends to reduce the pressure in the temperature controlling system.

The foregoing describes the operation of the parts of the apparatus in a general Way, but there are several factors which enter into the practice of the method with the apparatus by means of which the temperature of the combustion chamber walls of the engine may be controlled within relatively close minimum and maximum limits in order that the engine may be caused to operate at or very close to its temperature of most efllcient operation. In this connection, attention is invited to the fact that the present apparatus is a temperature controlling system rather than an engine cooling system as is true in conventional constructions. In a conventional engine a relatively large volume of cooling fluid is employed and this is necessary because of the inherent inefficiency of the system. 'Ihe flow of the fluid through the jackets of the engine is largely streamline, which` flow will be referred to later, in which case the rate of heat transfer is relatively slow. The rate of heat transference in a conventional engine is further reduced by the formation of a heat insulating film of steam against the faces of the water jacket adjacent the walls of the combustion chamber. Thus it is necessary to use a substantial volume of cooling liquid with the result that engine overheating may be prevented, but under most operating conditions the engine is operating at too low a temperature for eciency.

Moreover, the cooling liquid in conventional systems is circulated by a pump connected to the engine to be operated thereby, and accordingly the rate of circulation of the fluid depends directly upon engine speed and not upon the heat loads of the engine. If the engine is operating at a relatively high speed under minimum load conditions, therefore, the engine is maintained substantially below its temperature of efficient operation. On the other hand, if the engine is operating relatively slowly under heavy load conditions, heat will not be dissipated sufficiently rapidly and the engine will be operating at a temperature substantially above its temperature of maximum efficiency.

The present system takes into account, among other things, the difference in the heat transferring characteristics between a streamline flow thereof. 'I'he term "streamline as used herein refers to the flow of individual particles of fluid in more or less parallel lines as `distinguished from the turbulent flow offluid referred to below.

The difference between streamline and turbulent flow has been fairly well set forth in various texts dealing with this subject and reference is made to the expression, known as Reynolds number, DVe//r wherein D equals the diameter in feet ci a pipe or duct through which the fluid is flowing, V equals the velocity of" the fluid in feet per second, e equals density in pounds per square foot, and ,u equals viscosity in pounds per second per foot. A value of Reynolds number less than 2100 indicates streamline flow; from 2100 to 3100 indicates mixed flow; and above 3100 indicates turbulent flow. The Reynolds number for the average velocity of water through the cooling systems of present day engines indicates generally a streamline flow, or at best a mixed streamline and turbulent flow.

In order that an adequate idea may be gained as to the difference in heat transference under different conditions of flow of a cooling medium, attention is invited to a fairly well known equation by Maleev which gives a heat transfer between metal wall and water ranging from 150 to 330 B. t. u. for a water velocity of 9 feet per minute, and from 300 to 780 B. t. u. for a. Water velocity of 64 feet per minute. These velocities cover the average range of pl'esent day practice and the variations with the same velocities are due to sharp turns in the parts of the cooling system. Increasing the velocity to the point of turbulence produces the following results: The velocity of 1 lfoot per second through a 1A inch pipe results in the thermal conductivity of 604 B. t. u.; 6 feet per second, 2600 B. t. u.; and 10 feet per second, 3814 B. t. u.

From the foregoing it will be obvious, and it is fairly Well known, that stepping up the flow of a fluid into the range of turbulent flow increases the rate of heat transference far beyond the rate of increase in the flow of the fluid. Utilizing this principle, I have found that high temperatures and high pressures may exist in the cooling or temperature controlling fluid without increasing the cylinder wall temperature due to the increased rate of heat transference between the cylinder wall and the fluid. In other words, a relatively large body of cooling fluid ordinarily is required at a relatively low teml perature to prevent overheating of an engine,

whereas a proper turbulence in the flow of the fluid permits the use -of a relatively small volume of fluid at relatively high temperatures.

In this connection it is noted that while the circulating pump 24 for the temperature controlling fluid may be conveniently operated by the engine whereby its speed and pumping capacity varies with the engine speed, the rate of flow of the fluid through the helical tube I3 is governed directly by the temperature of the combustion chamber walls, such temperature being utilized in the manner described to determine the degree of opening movement of the valves 35 and thus determine the rate of circulation through the temperature controlling system. As the heat load on the engine increases, the valves 35 willbe progressively opened, thus decreasing the by-passing of the fluid through the relief valve 3| and increasing the rate at which the fluid is pumped through the' helical tube I3. The parts of the apparatus are designedv and adjusted so that the degree of turbulent flow increases at the proper rate in accordance with increased heat load conditions so as to predetermine a maximum temperature of the combustion chamber walls. In accordance with the foregoing discussion it will be apparent that the rate of heat transference between the combustion chamber walland the fluid in the tube i3 will be progressively accelerated to the point where the transferring of heat from the combustion chamber Walls to the fluid will prevent any further increase in combustion wall temperatures.

In its broadest aspects, therefore, the invention contemplates the use of a relatively small volume of heat-controlling fluid and the automatic controlling of the rate of flow of the fluid in accordance with the heat load conditions in the engine to predetermine maximum temperatures. It will be obvious that as the heat load decreases,

the valves '35 willbe moved toward their closed position, thus progressively reducing the rate of ow of ,the fluid as the heat load decreases. Under relatively low heat load conditions, therefore, the rate of flow will be reduced to the point where the reduced heat units in the combustion chamber walls may be readily transferred to the fluid Without substantially lowering the combustion chamber temperature as is true in conventional practice. Thus the apparatus functions in accordance with the method to provide a minimum operating temperature for the combustion chamber Walls under minimum heat load conditions.

Where water is employed as the temperature controlling iiuid it will -be apparent lthat steam will be generated in the coil I3, and this fact, together with the use of a turbulent oW of uid under substantial heat load conditions, permits the maximum temperature of the combustion chamber walls to be maintained at the desired point, it being apparent thatM substantial heat units are absorbed in converting the water into steam.

Under relatively heavy heat load conditions a ner control of the temperature may be provided by increasing the rate of condensation in the condenser 28. As the pressure in the pipe 2i increases, such pressure acts through the pipe 'I9 against the diaphragm I4 lto open the valves 'Il .to a greater extent, thus increasing the rate of flow of the condensing lud through the pipes 56. Thus an increased condensing action is provided upon the increasingof the rate of generation of steam in' the coil I3 incident to the presence of increasing heat loads.

Of course, it is not a function of the condenser to keep pressures in the temperature controlling system at or close to atmospheric pressure.

perature controlling system decrease, the-decreased pressure in the chamber IB permits `the flow of the condensing liquid will condense vapor in thetemperature controlling system at a sumcient rate to prevent any further increases in pressure to occur.

It will be apparent that as pressures in the -tem-` taining lower pressures in the coil I3 under heavy" heat load conditions the liquid therein will be converted into steam and thus absorb heat units .at a relatively rapid rate to prevent the maximum combustion chamber-Wall temperature from going above the desired point. Thus such point may be maintained vonly slightly above the temperature of maximum operating eiciency.

On the other hand, by maintaining higher pressures in the coil I3 under lower heat load conditions, the temperature of the liquid in the system must rise to a substantially higher point before, boiling. Thus it will be apparent that the rapid transferring of heat to the temperature controlling fluid under light heat load conditions due to the boiling of the liquid can be minimized and a greater proportion of the fluid in the coils I3 will be in liquid form with the temperature of such liquid higher than under heavier heat load conditions. Such higher temperature of the liquid will be closer to the temperature of the combustion chamber Walls andthe reduction in the. temperature differential thus provided'- minimizes Vthe rate of heat transfer andpermits a higher minimum temperature, closer to the temperature of maximum operating eiciency.

It vwill be apparent that the only part of the temperature controlling system in which the regy ulation of pressure and hence temperature is beneficial is in the portions of the uid tubes surrounding the combustion chamber. As will beccme apparent, the pressures in the pipe 2l may temperature, pressure and rate offlow of the fluid Attention is invited to the fact that the maintenance of pressure in the temperature controlling system is highly advantageous, and the system is preferably so designed and adjusted as to provide relatively high pressures under low heat load conditions on the engine. For example, the temperature control parts associated with the regulating system for the temperature controlling liquid are so designed that'the rate of ow of uid through the coil I3 will be sufficiently slow under low heat load conditions to cause a greater pressure and consequently a greater temperature in the temperature controlling fluid, particularly in that part of the ccil I3 surrounding the combustion chamber, than when operating under heavy heat load conditions. The operation of the valves 1I will limit the generation of pressure in the manner stated to prevent accumulation of dangerous pressures, and a distinct advantage is derived from causing the rate of flow of the temperature controlling fluid under low heat load conditions to be such as to permit increased pressures in the temperature controlling system, parin the fluid tubes around the combustion chamber.

It will b e assumed that a change in pressure in the v pipe 2l of 2 lbs. between minimum and maximum will operate the valves Il through their full range, and that a loss of head of 12 lbs. is required to force the luid through the coil ih the engine jacket at high heat loads because of the relatively high friction enccuntered by the iluid under such conditions, that is, -the friction occurring incident to the pumping of the ilu'id through the coils at a relatively high speed. It also will be assumed that a pressure of lbs. absolute is present in the temperature control system, at which pressure the temperature in the coils will be 328, this condition being present at minimum heat loads. Since the rate of ow under such conditions is slow, as governed by the temperature responsive means for operating the valves 35, the friction loss in the iiuid tubes will be small and therefore practically the same pressure will exist throughout the entire system.

When the engine is operating under high heat loads, however, the pressure in the pipe 2l, and consequently in the pipe v'19, will reach 102 lbs., which pressure will open the valves 7| to the point where the increased rate of condensation will reduce the uid pressure in the condenser and consequently in the pipe 20 leading from the engine, so that the pressure in the fluid leaving the engine will be reduced to 90 lbs., thus giving the pressure differential of 12 lbs. necessary to force the fluid through the coil, a condition referred to above. At such pressure the temperature in the coil I3 will drop to 320. Thus it will be apparent that under low heat load conditions relatively high pressures and consequently relatively high temperatures will exist in the coil I3 to minimize the temperature differential between the cylinder wall and the fluid and consequently reduce the rate of heat transfer. The higher pressure in the coil I3 likewise raises the boiling point of the fluid, thus further minimizing the rate of heat transference incident to converting the water into steam.l The practice of the method therefore keeps the temperature of the walls of the combustion chamber at a relatively high minimum temperature under light heat load conditions.

On the other hand, the lower pressures present in the coil I3 under heavy heat load conditions increases the rate of heat transference through the absorption of heat in converting the liquid into steam, the rate of heat transference being further increased by the greater temperature differential between the combustion chamber walls and the fluid. Moreover, under such heavy heat load conditions, the rate of flow of the fluid through the coil I3, as previously stated, is at least partly turbulent, thus providing for an even greater rate of heat transference. Thus the method operates to maintain a relatively low maximum temperature in the combustion chamber walls under maximum heat load conditions. Accordingly it will be apparent that the present invention operates very efficiently to maintain both the minimum and maximumtemperatures of the combustionchamber walls very close to the temperature of maximum engine eflciency.

It will be apparent that the present invention operates to maintain the cylinder wall at a relatively uniform temperature as distinguished from merely controlling the temperature of the uid, and in the preferred practice of the method, the temperature of the fluid rises and falls inversely With the rise and fall of the heat developed in the engine. `Proper design and adjustment provides a concrete degree of turbulence in the fluid in accordance with definite variations in heat loads, and accordingly the system operates to induce a rate of heat transfer from cylinder wall to fluid having a substantially constant ratio to the heat units to be removed from the cylinder wall.

The expansion chamber 30 provides ample space for the expansion of the fluid in the temperature control system` as pressure therein increases. The size of the expansion chamber, of course, affects the graduation in pressures incitrapped in the chamber.

dent to the generation of steam in the coil I3 and assists in providing the ne controlling of the temperature by the system. It will be apparent that the system provides for the controlling of the rate of heat transference principally by controlling the rate and nature of the flow of fluid through the coil I3, the rate of flow being increased as heat loads increase in the engine and the cross-sectional area of the coil I3 being so related to the flow of fluid as to cause the flow to change to a turbulent flow or a mixed streamline and turbulent flow depending upon the rate at which it is necessary to carry off heat under the heat conditions in the engine.

The designing and adjustment of the parts by which greater pressure is present in the coil I3 under light heat load conditions further increases the flneness of the controlling of the temperatures of the combustion chamber walls, as explained above. The use of the body of metal I2 of high heat conductivity is useful in assisting in the transferring of heat from the cylinder liner II to the tube I3 from which the heat is efliciently transferred to the fluid therein. It will be obvious that the use of the metal I2 is desirable, but not necessary.

There are important advantages inherent in the method and apparatus other than the maintenance of the engine at or close to its temperature of maximum efliciency. For example, the maintenance of uniform temperatures permits the use of a thinner cylinder wall, the slightly different temperatures between the cylinder wall and the cooling medium reducing the internal stresses in the metal of the liner. Moreover, the use of a smaller volume of temperature controlling fluid permits the engine to warm up more rapidly than a conventional engine, and the advantages of the rapid warming up of an internal combustion engine are well known.

The system shown in Figure 3 is wholly practicable and is highly advantageous over conventional systems, although it does not provide as fine a temperature control as the system previously described, as will become apparent. In the operation of the modified form of the invention, the system is filled with water or other temperature controlling fluid through the cap 9|, the water filling the condenser 81, coils 83 and 84 and the piping connections 85 and 88. The normal level of the water when the chamber is employed as an expansion chamber is indicated by the numeral 92. It will be apparent that the system is entirely sealed from the atmosphere under normal conditions. As the engine warms up the water in the coils 83 and 84 absorbs heat as will be apparent, and is finally at least partially converted into steam, depending upon the heat load inthe engine. The expansion in the system incident to the conversion of some of the water into steam causes an increase in the specific volume of the fluid, thus resulting in an increase in pressure in the entire system, which is closed as previously stated.

It will be apparent that the increase in the volume of the fluid raises the level of the fluid in the chamber 90 and compresses the air The continued expansion of the cooling fluid and the continued increase in the pressure of the air in the chamber 90 finally reaches a point of equilibrium at which point steam will be condensed at a rate equal to the generation of steam in the coils 83 and 84. As the fluid is heated in the coils its density decreases, and this obviously is particularly true after the generation of steam commences.

The system shown in Figure 3 is purely thermo-syphonic in action, and prior to the generation of steam in the coils 83 and 84, the unbalancing of the two columns of the system obviously is such as to only slightly unbalance these columns to cause a relatively slow circulation of fluid. The generation of steam in the coils 83 and 84 further unbalances the two columns and thus materially increases the speed of circulation of fluid, the unbalancing of the two columns and the rate of fluid flow obviously continuing to increase as the generation of steam in the coils increases. The theoretical maximum rate of fluid circulation obviously will be reached whenV all of' the fluid in the coils is converted into steam.

Since steam at 350 F. weights approximately im of an equal volume of water. it will be apparent that the rate of circulation' in the system, under heavy heat load conditions, will be far greater than that which takes place in a conventional thermo-syphonic engine cooling system. The rate of circulation has been found ample to cause turbulence in the water flowing through the coils 83 and 84. This turbulence increases as the columns of the system are increasingly unbalanced, which operation is due, in turn, to increasing heat load conditions. As previously explained, the rate of heat transference is greatly accelerated by the turbulent flow of the fluid and thus it follows that the greater the heat load on the engine the greater will be the rate of heat transference to provide the desired maximum temperature of the cylinder walls. The check valve 86 may be provided to prevent any surging in the pipe 85, as will be apparent.

While the condenser in Figure 3 has been shown approximately at the level of the top of the engine cylinder, attention is invited to the fact that the condenser may be placed at any elevation to provide the necessary head whereby the two fluid columns may be sufliciently unbalanced to circulate the fluid at the desired rate.

The modified form of system does not as closely control the difference between minimum and maximum combustion chamber Wall temperatures as the previously described form of the invention. This is due to the fact that the pressure in the system is at its -maximum when the engine .heat load is at maximum, while the pressure in the system obviously is at its minimum under minimum heat load conditions. However, the system is advantageous because of its simplicity, and is a very distinct improvement over conventional practice. It will be apparent that the system operates automatically to increase the rate of flow of fluid under increased heat load conditions, and the system is so designed withrelation to the cross-sectional area of the coils 83 and 84 as to provide the necessary turbulence of the fluid under increasing heat loads to accomplish the highly desirable increase in the rate of heat transference from the cylinder wall to the fluid, thus preventing the cylinder wall temperature from going above a given maximum. While there is ya greater differential between minimum and maximum cylinder wall temperatures inthe modied form of the invention, suchl form includes other advantages of the previously described system in that it reduces internal stresses in the cylinder wall; it permits the use of a relatively small volume of temperature controlling fluid; and it permits the engine to warm up more rapidly than is true in conventional systems.

Instead of employing an expansion chamber 90 large enough to provide suilcient space for the expansion of the cooling huid, a smaller chamber may be employed with the member 9| forming a conventional relief valve'which may be of any standard adjustable type. Under such conditions, as pressure builds up in the system, the air will be compressed to the setting of the relief valve, after which further compression of the air will result in the discharge of excess air from the system. This operation is advantageous in that it provides means for controlling the temperature of the fluid being circulated. It is well known that steam at atmospheric pressure in contact with water will not rise aboue 212 F. At 100 lb. absolute, the temperature will be 328 vention is not limited to the application of the F.; at 200 1b. absolute the temperature-will be 382 F. and so on. To obtain a temperature above 212 F., therefore, the system must be closed to permit the building up of higher pressures. The pressure in the present system, and consequently the temperature of the fluid medium, can be readily controlled by adjusting the valve member 9|. Such regulation without adjustment, can be obtained by employing air chambers of different sizes.

Whichever way the form of the invention shown in Figure 3 is used, no water pump is required for the circulation of uid, and the system provides far more rapid circulation than is ordinarily accomplished in a thermo-syphonic cooling system. Moreover, the system is sealed and accordingly prevents any loss of the temperature controlling fluid, and only asmall condenser need be employed.

The use of tubing for the fluid circulating passages in the engine is advisable under most conditions because such structure obviously is adapted to withstand the maximum pressures which will occur in the system. For smallerengines operating with moderate pressures the structure in Figure 4 is wholly satisfactory. In such structure the jacket 93 is helically grooved to form a helical passage when the liner 94 is placed in position. In such a construction the temperature controlling fluid is in direct contact with tli'e cylinder liner, thus providing an effective heat transferring relationship.

By using metals of high thermal conductivity for the cylinder liners of the diiferent forms of the invention, the temperature of the cooling fluid undoubtedly can be carried as high as 400 F., thus further reducing the temperature differentials between the cylinder wall and the cooling fluid. If water is used as the cooling uid, this would result in a pressure of 250 lb. absolute in the cooling system. Of course. liquids other than water may be employed in the system, such as several of the commercially available preparations employed as anti-freeze solutions, at least'one of which has a boiling point at 387 F. at atmospheric pressures. Such liquids may be employed to operate the systems at lower pressures.

It is not wholly essential in the practice of the invention that the fluid conduits shown and described be employed in both the cylinder proper and the cylinder head. For example, in one installation which has been developed, the uid conduit is employed in connection with the cylinder head while the cylinder wall is water cooled in the usual manner. Fairly satisfactory results can be obtained under such conditions'since a large part of the heat loss ordinarily occurs through the cylinder head of an engine. It is to be understood therefore that the present incooling fluid conduit in both the cylinder wall and cylinder head since it is applicable to either of these elements. Where such an expression as a fluid conduit in said combustion chamber wall occurs in the claims it is understood that this expression is intended to cover either the cylinder wall properv or the cylinder head, since this element forms a wall of the combustion chamber, and the expression referred to is likewise intended to cover both the cylinder head and cylinder wall. i

As previously stated, water is preferably used as the temperature controlling fluid for the engine. However, it has been pointed out that other fluids may be used and where reference is made to steam in the claims lt is to be understood that this expression is intended to cover not only the conversion of water into steam but also the vaporizing of other liquids which may be used in the system.

While I have disclosed the preferred practice of the method and the preferred embodiments of the apparatus, itis to be understood that the details of procedure of the method and the shape, size and arrangement; of parts of the apparatus may be variously modified without departing from the` spirit of the invention or the scope of the subjoined claims.

I claim:

1. In an internal combustion engine having a combustion chamber provided with a wall, a fluid conduit in intimate heat transferring association with said combustion chamber-wall, means for effecting a flow of fluid through said conduit, and means in contact with and controlled by the temperature of said combustion chamber wall for controlling the rate of flow of fluid through said conduit.

2. In an internal combustion engine having a combustion chamber provided with a wall, a fluid conduit in intimate heat transferring association with said combustion chamber Wall, means for effecting a flow of fluid through said conduit, and means in contact with and controlled by the temperature of said combustion chamber wall for causing the rate of flow of fluid to increase as the combustion chamber wall temperature increases and to cause the rate of fluid flow to de- ,crease as the combustion chamber wall temperature decreases.

3. In an internal combustion engine having a combustion chamber provided with a, wall, a tubular conduit in intimate heat transferring association with said combustion chamber wall, means for effecting a flow of fluid through said conduit, said conduit being of such a cross-sectional area that the flow of fluid therethrough becomes at least partially turbulent when the rate of fluid flow exceeds a given rate, to thereby increase the rate of heat transference between said combustion chamber wall and the fluid in said conduit, and means in contact with and controlled by the temperature of the combustion chamber wall to render said first named means effective for increasing the rate of fluid flow as the combustion chamber Wall temperature increases, with the rate of fluid flow exceeding said given rate at relatively higher combustion cham-v ber wall temperatures.

4. In an internal combustion engine having a combustion chamber provided with a wall, a tubular conduit in intimate heat transferring 'association with said combustion chamber wall, means for effecting a flow of vfluid through said conduit, means in contact with and controlled by the temperature of the combustion chamber wall for causing the rate of fluid flow to increase as the combustion chamber wall temperature in-V creases and to decrease as the combustion chamber wall temperature decreases, and means governing the pressure of the fluid in said conduit.

5. In an internal combustion engine having a combustion chamber provided with a wall, a tubular conduit in intimate heat transferring association with said combustion chamber wall an'd of such cross-sectional area and length that steam will be generated therein, cooperating means for effecting a flow of fluid through said conduit with the rate of flow increasing as the combustion chamber wall temperature increases and decreasing as the combustion chamber wall decreases, and means governing the pressure of the fluid in said conduit whereby such pressure progressively increases as the combustion chamber wall temperature progressively decreases.

6. In an internal combustion engine having a combustion chamber provided with a Wall, a tubular conduit in. intimate heat transferring association with said combustion chamber Wall and of such cross-sectional area and length that steam will be generated therein, cooperating means for effecting a flow of fluid through said conduit with the rate of flow increasing Vas the combustion chamber wall temperature increases, a circulatory system in which said conduit is arranged, a condenser in said circulatory system, and means responsive to pressures in said system for determining the rate of condensation in said condenser. f

7. In an internal combustion engine having a combustion chamber provided with a wall, a tubular conduit in intimate heat transferring association with said combustion chamber wall and of such cross-sectional area and length that steam will be generated therein, cooperating means for effecting a flow of fluid through said conduit with the rate of flow increasing as the combustion chamber wall temperature increases. a circulatory system in which said conduit is 1 arranged, a condenser in said circulatory system, and means responsive to pressures in said system for determining the rate of condensation in said .and the fluid in said conduit.

-8. In an internal combustion engine having a combustion chamber provided with a wall, a tubular fluid conduit in intimate heat transferring association with said combustion chamber wall and -of such cross-sectional area and length that steam will be generated therein, means for effecting a flow of fluid through said conduit, means for controlling the rate of flow of fluid through said conduit whereby the rate of flow progressively increases under progressively increasing combustion chamber wall temperatures, and an expansion chamber accommodating the expansion of the fluid incident to the generation of steam in said conduit to graduate the temperatures at which steam will be generated under varying pressure conditions in said conduit.

9. In an internal combustion engine having a combustion chamber provided with a wall, a tubular fluid conduit in intimate heat transferring association with said combustion chamber Wall and of such cross-sectional area and length that steam will be generated therein, a circulatory system in which said conduit is connected, means ,for effecting a flow of fluid through said system, means for controlling the rate of flow of fluid whereby the rate of flow progressively increases as the combustion chamber wall temperature increases, an expansion chamber accommodating the expansion of the fluid incident to the generation of steam in said conduit to determine the temperature at which steam will be generated therein, a condenser in said circulatory system, and means responsive to pressures in said system for determining the rate of condensation of v steam in said condenser.

10. In combination With an internal combusratio to the heat units to be removed from the combustion chamber Wall to maintain a relatively uniform temperature of the combustion chamber wall.

11. In an internal combustion engine having a combustion chamber provided with a wall, a body of metal of high thermal conductivity in intimate contact with said combustion chamber wall, and a iuid conduit at least partially imbedded in said body of metal and surrounding said combustion chamber wall.

12. In an internal combustion engine having a combustion chamber provided with a wall, a body of metal of high thermal conductivity in intimate contact with said combustion chamber wall, a fluid conduit at least partially imbedded in said body of metal and surrounding said combustion chamber wall, the cross-sectional area of said conduit being such that the flow of uid therethrough becomes at least partially turbulent when the rate of flow exceeds a given rate, means for eecting the ow of uid through said condult,said means being eective for causing fluid to now through said conduit in excess of said given rate, and means contacting with and responsive to the temperature of said Acombustion chamber Wall `for controlling the rate of flow through said conduit with the rate of flow exceeding said given rate at relatively high combustion chamber wall temperatures.

13. In an internal combustion engine having a combustion chamber provided with a wall, a

iluid conduit in intimate heat transferring association with said combustion chamber wall, means for eiecting a flow of uid through said conduit, means controlled by the temperature of said combustion chamber wall for causing the rate of ilow of fluid through said conduit to increase as the combustion chamber wall temperature increases, a circulatory system in which said conduit is arranged, a condenser in said circulatory system, and means responsive to pressures in said system for determining the rate of condensation in said condenser.

14. In an internal combustion engine having va combustionchamber provided with a wall, a

fluid conduit in intimate heat transferring relationship with said combustion' chamber wall, said conduit being of such construction and arrangement that steam will be generated therein, a circulatory system in which said conduit is arranged a condenser in said circulatory system, and means responsive to pressures at a predetermined point in said system for determining the rate of condensation in said condenser, the varying rate of condensation in said condenser being such that pressures in said conduit progressively increase as combustion chamber wall temperatures progressively decrease to thereby increase the boiling point of fluid in said conduit at relativelylower combustion chamber wall temperatures.

15. In an internal combustion engine having a combustion chamber provided with a wall, a uid conduit in intimate heat transferring relationship with said combustion chamber wall, said conduit being of such construction and arrangement that steam will be generated therein, means for effecting 'a flow of uid through said conduit with the rateof Iiow increasing as the combustion chamber wall temperature increases, a circulatory system in which said conduit is arranged, a condenser in said circulatory system, and means responsive to pressures in said system for determining the rate of condensation in said condenser, the varying rate of condensation in said condenser and the varying rate of heat transference between the combustion chamber wall and the fluid in said conduit incident to variations in the rate of uid flow being so related to each other that pressures in said conduit progressively increase' as combustion chamber wall temperatures progressively decrease to thereby increase the boiling point of fluid in said conduit at relatively lower combustion chamber wall temperatures to reduce the temperature diiferential between the combustion chamber wall and the uid in said conduit.

16. In an internal combustion engine having a combustion chamber provided with a wall, a tubular fluid conduit in intimate heat transferring association with said combustion chamber wall and of such cross-sectional area and length that steam will be generated therein, a circulatory system in which said conduit is connected, means for eiecting a now of fluid through said system, land means constructed and arranged to be subject to temperatures in said combustion chamber wall to change the rate of now of fluid and thus induce a new rate of heat transfer from said combustion chamber wall to the iiuid, which will tend to return the combustion chamber wall to y its original temperature.

17. In an internal combustion engine havingr a combustion chamber provided with a wall, a tubular conduit in intimate heat transferring association with said combustion chamber wall and of such cross-sectional area and length that steam will be generated therein, cooperating -means for eecting a ow of fluid through said conduit, means having a portion in contact with the combustion chamber wall for controlling the rate of flow of the uid with the rate of ow increasing as the combustion chamber wall temperature increases and decreasmg as the combustion chamber wall temperature decreases, and means governing the pressure of the uid in said conduit whereby such pressure progressively increases as the combustion chamber wall temperature progressively decreases.

JOSEPH G. 

